This invention relates to improvements in conveyor systems of the power and free type.
Such conveyor systems conventionally include a carrier track, carriers each having a driving trolley supported on the carrier track, a power track spaced vertically from the carrier track, and carrier propelling means mounted on the power track, the propelling means being normally driven in a forward direction and including pusher members projecting toward the carrier track. The driving trolley has a driving member which is movable between operable and non-operable positions with respect to a pusher member and which is biased to the operable position.
Other conventional features of such conveyor systems include:
1. The capability of stopping and accumulating carriers by causing their driving members to be moved to nonoperable relation with the pushers; and
2. In more complex systems, the capability of providing transfer zones to which a carrier is propelled by a forwarding pusher and from which the carrier is to be propelled by a receiving pusher, the forwarding and receiving pushers usually (but not necessarily) being part of separately driven forwarding and receiving propelling means so that carrier speed, or relative spacing, or both, may be varied as desired throughout the system.
Reference is made to the following U.S. patents for a more complete disclosure of the features summarized above:
U.S. Pat. No. 3,044,416--The driving member of a carrier driving trolley is connected to a forwardly projecting lever which is engageable by a rearwardly projecting actuator on a preceding carrier to move the driving member to non-operable relation with a pusher member. Bumpers on the trolleys prevent damage to the lever which also serves as a counterweight to bias the driving member to the operable position relative to a pusher member.
U.S. Pat. No. 3,434,431--A stop member, positionable in the path of forward movement of a carrier driving trolley, contacts a cam surface on the driving member to move it out of engagement with a pusher member and is abutted by a holdback dog to stop the driving trolley. In this disclosure, a secondary stopping device is provided to insure that the desired abutting engagement of the stop member takes place.
U.S. Pat. Nos. 3,229,645 and 3,314,377--These patents relate to transfer zones through which carriers are propelled by forwarding and receiving pusher members. Each carrier is provided with a secondary driving member which is located rearwardly of a main driving member and is engageable by a forwarding pusher member to advance the carrier through the transfer zone. Interference between pusher and driving members is prevented by dimensional differences in the driving and holdback members of the carrier and in the spacing between the carrier track and the forwarding and receiving power tracks.
All of the results obtainable by the teachings of these prior patents are achieved in the conveyor systems of the present invention by a relatively less complex construction which offers several additional constructional and operational features including:
1. The capability of providing two types of conveyor systems, one having the power track located below the carrier track and the other having the power track located above the carrier track as in the prior patents mentioned above;
2. Transfer zones at which carriers can be accumulated and through which carriers can be propelled by forwarding and receiving pusher members without requiring a secondary driving member on each carrier and without interference between the carrier driving member and the forwarding and receiving pusher members;
3. Stops which positively arrest forward movement of a carrier; and
4. Carrier bumpers and accumulating mechanism which are located within a protected space partially enclosed by the structural members forming the carrier track.